DEAR DR. ROACH: In a recent column, you said that using peroxide in the ear is a bad home remedy. Would you please expand on this subject? My children grew up with me using peroxide to clean excessive wax from their ears, and they now use the same remedy on my grandchildren.

ANSWER: Most earwax does not need to be removed. It should be removed only when there are symptoms (such as poor hearing, ear pressure or pain, and sometimes itchiness or dizziness), and when it is clear that the symptoms are coming from excess earwax. This requires a look in the ear, since similar symptoms may come from infection.

Hydrogen peroxide is too harsh to put on skin. Doctors may use it to irrigate the ear canal while looking into the ear, but it is diluted, usually 1:10. Over-the-counter earwax preparations, such as carbamide peroxide, may also be recommended once the diagnosis is clear.

DEAR DR. ROACH: My son is taking hemp-based CBD oil for depression. He purchased this at a health food store. His doctor prescribed pills that he was unable to tolerate due to suicidal thoughts. He is unable to go outside when taking CBD. We would like to know if it will show up in a drug test as part of a job interview. Should he be taking it? — D.

ANSWER: There are animal studies and some preliminary data suggesting that cannabidiol, a nonpsychoactive substance found in cannabis, might be effective for anxiety and depressive disorders. I hope that CBD will be proven to be a useful treatment for depression, as what we have now certainly isn’t perfect. However, there are not yet high-quality studies supporting this use. The fact that your son can’t go out while taking the CBD suggests to me that it may not be effective. While the pills he had previously cannot be used, there are many treatments available for depression that have better safety and effectiveness data than CBD.

Most forensic drug testing uses THC and its metabolites, so if what your son is taking is truly CBD, then it should not be identified during testing as THC. There is a chance that the “CBD oil” he purchased has THC in it: In one study, 57% of CBD oils sold were found to have measurable THC, which would show up on a drug test. Unfortunately, 25 percent of the oils contained no CBD at all.

I remain convinced that these drugs, THC and CBD, need to be properly studied, and when found to be useful, tested for purity and content in the same way as pharmaceuticals.

DR. ROACH WRITES: I received a lot of mail from readers about a column in which a reader described realistic hallucinations upon awakening. I was concerned about Lewy body disease, a form of dementia with prominent visual hallucinations. The most common condition readers were concerned about was Charles Bonnet syndrome, a type of visual hallucination found in people with vision loss. It’s not well known, so I was surprised that so many people wrote to me about it, particularly when the original letter didn’t say anything about vision loss.

The answer, as diagnosed by my reader’s neurologist, turned out to be hypnopompic hallucinations (hypnagogic hallucinations are a similar issue, but these occur upon falling asleep). M.O., a sleep technician, and P.W. from California wrote to me with the same diagnosis. These can occur in sleep apnea, which several people wrote about, and several said treatment stopped these hallucinations. They can also be associated with neurological disease, such as Parkinson’s disease, Guillain-Barre syndrome and narcolepsy.